DESCRIPTION: (Adapted From The Applicant's Abstract.) A series of experiments is proposed to investigate the basic speech perception capacities of infants and the role that such capacities play in acquiring a native language. The proposed research has several objectives. The first is to gain a fuller understanding of basic processing resources that infants have for perceiving speech in their natural environments. Accordingly, some of the proposed studies will investigate how memory and attentional demands affect infants' perception of speech sounds. Information from these investigations achieving the remaining objectives which relate to understanding the role of speech perception capacities in acquiring various elements of the structural organization of a native language. One such objective is to determine when infants learn about regularly occurring patterns involving segmental and suprasegmental features of native language utterances. This in turn, bears on another aim of the proposed research, which is to determine whether sensitivity to such regularities provide the language learner with clues about the underlying organization of utterances in the language. In particular, are there cues in speech that aid learners in discovering linguistically relevant units and their relations to each other? A related objective is to delineate the role that speech perception capacities play in learning words. Other related studies will focus on the nature of the information that is stored in words. Several different methods will be used in the proposed studies. Two- month- olds will be tested using versions of the high-amplitude-sucking procedure. Infants, ranging from 4.5 to 11 months of age, will be tested with versions of the Headturn Preference Procedure. Both procedures are versatile enough to be used not only to examine perceptual capacities, but also to investigate memory for speech information. Speech perception is an important aspect of normal human communication. The proposed studies are intended to clarify the role of speech perception in language acquisition. Not only does such information provide background about the normal range of capacities during the first year, but it helps to identify critical processes for the successful development of communication skills. Such information has practical relevance to those involved in the formation of treatment programs for communication disorders.